get-developers: fix handling of syntax error

When getdeveloperlib.parse_developers doesn't find anything, the script
tries sys.exit(1) but sys is not imported.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

utils/get-developers

@@ -2,6 +2,7 @@
 
 import argparse
 import getdeveloperlib
+import sys
 
 def parse_args():
     parser = argparse.ArgumentParser()